JPH0735303B2 - Method for manufacturing boron nitride sintered body - Google Patents
Method for manufacturing boron nitride sintered bodyInfo
- Publication number
- JPH0735303B2 JPH0735303B2 JP62259653A JP25965387A JPH0735303B2 JP H0735303 B2 JPH0735303 B2 JP H0735303B2 JP 62259653 A JP62259653 A JP 62259653A JP 25965387 A JP25965387 A JP 25965387A JP H0735303 B2 JPH0735303 B2 JP H0735303B2
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- Japan
- Prior art keywords
- boron nitride
- sintered body
- powder
- boron
- weight
- Prior art date
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は耐熱性、耐熱衝撃性、潤滑性、耐蝕性、電気絶
縁性、熱伝導性にすぐれたセラミック材料である高純度
六方晶窒化ホウ素（以下窒化ホウ素と称する）焼結体の
製造方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a high-purity hexagonal boron nitride which is a ceramic material excellent in heat resistance, thermal shock resistance, lubricity, corrosion resistance, electrical insulation, and thermal conductivity. The present invention relates to a method for manufacturing a sintered body (hereinafter referred to as boron nitride).
窒化ホウ素は熱的、化学的、電気的特性に優れ、かつ潤
滑性を有し、機械加工が容易にできるなど多くのすぐれ
た性能を備えたセラミックス材料である。Boron nitride is a ceramic material having many excellent properties such as excellent thermal, chemical and electrical properties, lubricity, and ease of machining.
即ち、熱的には不活性雰囲気中では約3000℃まで安定で
ありかつ熱伝導率がきわめて高く熱衝撃抵抗が大きく、
また、溶融金属にぬれ難く、反応しないなど化学的な安
定性にも優れており、耐熱、耐蝕材料としての用途が非
常に広い。また熱的安定性に加えて潤滑性に優れている
ので、高温潤滑材として貴重な材料でもある。That is, it is thermally stable up to about 3000 ° C in an inert atmosphere, has extremely high thermal conductivity, and has high thermal shock resistance,
In addition, it has excellent chemical stability such that it is difficult to wet the molten metal and does not react, and its application as a heat resistant and corrosion resistant material is very wide. Further, it is excellent in lubricity in addition to thermal stability, so it is a valuable material as a high temperature lubricant.
更に電気抵抗が極めて大きく、高温になっても変化が小
さいことから広い温度範囲で使える電気絶縁材料でもあ
る。Furthermore, since it has an extremely high electric resistance and its change is small even at high temperatures, it is an electric insulating material that can be used in a wide temperature range.
ところが窒化ホウ素は優れた熱的、化学的特性を有する
反面、難焼結性であり、焼結体を製造するには高温及び
機械的高圧処理を必要としている。例えば工場規模で窒
化ホウ素焼結体を製造する場合には、窒化ホウ素製造時
に未反応B2O3を残した状態の窒化ホウ素原料をホットプ
レスにより加熱加圧したり、あるいは窒化ホウ素粉体に
アルカリ土類金属ホウ酸塩例えばMgO・B2O3、CaO・B
2O3、SrO・B2O3等をバインダーとして数％から10数％混
合し黒鉛ダイスに詰めて200から400kg/cm2で加圧しなが
ら高周波誘導加熱炉を用いて2000℃付近の温度で加熱さ
せる方法（特公昭49-40124号）が取られている。However, while boron nitride has excellent thermal and chemical properties, it is difficult to sinter, and high temperature and mechanical high pressure treatments are required to produce a sintered body. For example, when manufacturing a boron nitride sintered body on a factory scale, the boron nitride raw material in a state where unreacted B 2 O 3 remains during the production of boron nitride is heated and pressed by hot pressing, or boron nitride powder is treated with an alkali. Earth metal borates such as MgO ・ B 2 O 3 , CaO ・ B
2 O 3 , SrO / B 2 O 3 etc. are mixed as a binder in the range of several% to 10% and packed in a graphite die and pressurized at 200 to 400 kg / cm 2 while using a high frequency induction heating furnace at a temperature of around 2000 ° C. The method of heating (Japanese Patent Publication No. Sho 49-40124) is used.
又本願発明者はバインダーの少ない窒化ホウ素焼結体の
製造法を開発したが（特開昭59-162179）、この方法に
おいても焼結はホットプレスに限定されている。Further, the inventor of the present invention has developed a method for producing a boron nitride sintered body having a small amount of binder (Japanese Patent Laid-Open No. 59-162179), but in this method as well, sintering is limited to hot pressing.
前記の従来方法のうち未反応B2O3を残した状態の窒化ホ
ウ素をホットプレスの出発原料としたり、アルカリ土類
金属塩をバインダーとして多量混合する方法には次のよ
うな欠点がある。Among the above-mentioned conventional methods, the method in which boron nitride in a state where unreacted B 2 O 3 is left is used as a starting material for hot pressing or a large amount is mixed with an alkaline earth metal salt as a binder has the following drawbacks.
これらの従来法で得られた焼結体には数％から10数％の
B2O3を主体とした酸化物が混存することになり、窒化ホ
ウ素本来の優れた特徴が充分に発揮できない。特に、不
活性雰囲気中では約3000℃付近まで安定な窒化ホウ素も
B2O3を主体とする酸化物バインダーが混在した焼結体で
は千数百度よりバインダーが吹き出し、接触している別
の材料を反応したり、バインダーの揮散によって付近を
汚したり、又、窒化ホウ素焼結体自体に亀裂が生じるな
どの現象が生じるので使用温度が大幅に限定されている
のが現状である。Sintered bodies obtained by these conventional methods have several percent to ten percent
Oxides mainly composed of B 2 O 3 are mixed, and the original excellent characteristics of boron nitride cannot be fully exhibited. In particular, boron nitride that is stable up to about 3000 ° C in an inert atmosphere
In a sintered body mixed with an oxide binder mainly composed of B 2 O 3 , the binder blows out from a few thousand degrees to react with another material that is in contact with it, stain the neighborhood by volatilization of the binder, or nitride it. At present, the operating temperature is greatly limited because a phenomenon such as cracking occurs in the boron sintered body itself.
従って、B2O3を主体とする比較的低融点バインダーが含
有されることに起因する上記の欠点がない窒化ホウ素
が、しかも、常圧焼結法においても製造できればこれま
でにない高品質の焼結体が安価に得られる。Therefore, if boron nitride, which does not have the above-mentioned drawbacks due to the inclusion of a relatively low-melting-point binder mainly composed of B 2 O 3 , can be produced even by the atmospheric pressure sintering method, it has a high quality as never before. A sintered body can be obtained at low cost.
なお本発明者らによる前記の特開昭59-162179に開示の
方法はバインダーの含有量は少ないが、焼結はホットプ
レスに限られる。The method disclosed in the above-mentioned JP-A-59-162179 by the present inventors has a small binder content, but sintering is limited to hot pressing.
本発明者はホットプレスは勿論のこと常圧でも高密度
で、高強度であり、かつ高純度の窒化ホウ素焼結体を得
る製造法を開発することを目的として研究を行い、先に
アルカリ土類金属化合物を配合して成形・焼結する方法
を出願した（特開昭64-3074号公報（特願昭62-156563
号））。The present inventor conducted research for the purpose of developing a manufacturing method for obtaining a high-purity boron nitride sintered body having high density and high strength not only in hot pressing but also in normal pressure. We applied for a method of compounding and sintering a metal compound (Japanese Patent Application Laid-Open No. 64-3074 (Japanese Patent Application No. 62-156563).
issue)).
しかし本件発明者はさらに研究を進め、従来のバインダ
ーを用いる製造法に代って特定の窒化ホウ素粉末、すな
わち比較的比表面積の小さい窒化ホウ素粉末（以後窒化
ホウ素粗粉と称する）に非常に微細な窒化ホウ素粉末
（以下窒化ホウ素超微粉と称する）と炭化ホウ素粉末を
配合して成形し、窒素又は窒素を含有する非酸化性雰囲
気で焼成することによりアルカリ土類金属化合物のよう
な成分を添加することなく目的の焼結体が得られること
を発見して本発明を完成した。However, the inventor of the present invention further researched, and instead of the conventional manufacturing method using a binder, a very fine powder of a specific boron nitride powder, that is, a boron nitride powder having a relatively small specific surface area (hereinafter, referred to as coarse boron nitride powder) was obtained. Boron nitride powder (hereinafter referred to as ultrafine boron nitride powder) and boron carbide powder are blended and molded, and a component such as an alkaline earth metal compound is added by firing in nitrogen or a non-oxidizing atmosphere containing nitrogen. The present invention has been completed by discovering that a desired sintered body can be obtained without doing so.
すなわち、本願発明の要旨はBET法比表面積が１〜30m2/
gの粉末と100m2/g以上の粉末を配合してなる六方晶窒化
ホウ素の混合粉末60〜99.9重量％と炭化ホウ素粉末0.1
〜40重量％を配合して成形し、窒素又は窒素を含有する
非酸化性雰囲気中で炭化ホウ素を窒化ホウ素に変換させ
る温度以上で焼成することを特徴とする窒化ホウ素焼結
体の製造方法にある。That is, the gist of the present invention is that the BET specific surface area is 1 to 30 m 2 /
60 to 99.9% by weight of hexagonal boron nitride mixed powder prepared by blending g powder and 100 m 2 / g or more powder and boron carbide powder 0.1
~ 40 wt% compounded and molded, in a method for producing a boron nitride sintered body, characterized by firing at a temperature above the temperature for converting boron carbide to boron nitride in nitrogen or a non-oxidizing atmosphere containing nitrogen is there.
次に本発明について詳細に説明する。Next, the present invention will be described in detail.
窒化ホウ素粉体は一般にはホウ素、無水酸化ホウ素又は
ホウ砂をアンモニアガス中で加熱するか或いはアンモニ
アガスを発生する含窒素有機化合物と混合して加熱し、
得られた窒化ホウ素を再度窒素雰囲気中で高温で加熱し
て結晶性を高め製品としている。このようにして得られ
た市販の窒化ホウ素は通常結晶サイズが１μを越える程
度である。Boron nitride powder is generally heated by heating boron, anhydrous boron oxide or borax in ammonia gas, or by mixing with a nitrogen-containing organic compound that generates ammonia gas,
The obtained boron nitride is heated again in a nitrogen atmosphere at a high temperature to enhance the crystallinity and obtain a product. The commercially available boron nitride thus obtained usually has a crystal size of more than 1 μm.
ここで、上記のような窒化ホウ素粉末に特定の物質を混
合し、再度加熱して結晶を成長させると非常に充填性が
高められ、このような粉末を粗粉の原料として用いるこ
とは、生成形体の密度を高め、ひいては焼結体密度を高
める点で有利である。例えば市販の窒化ホウ素粉末に９
重量％のホウ酸とCaO換算で５重量％となるように炭酸
カルシウムとフッ化カルシウムを加え、ブリケットとな
し窒素雰囲気中で2000℃に加熱すれば結晶サイズは20〜
40μとなる。Here, when the boron nitride powder as described above is mixed with a specific substance and heated again to grow a crystal, the filling property is greatly improved, and using such a powder as a raw material for the coarse powder results in generation. It is advantageous in increasing the density of the shaped bodies and, in turn, the density of the sintered body. For example, commercially available boron nitride powder
If you add calcium carbonate and calcium fluoride to 5% by weight of boric acid and CaO in terms of CaO and heat to 2000 ° C in a nitrogen atmosphere without briquettes, the crystal size will be 20 ~.
40μ.
但し、このようにして得られた粉末をそのまま又は粉砕
して用いると焼結体中に多量のアルカリ土類金属ホウ素
酸塩を残留させることになる。このことは、焼結体を千
数百度以上に加熱した場合に液相となって吹き出す場合
があるので、アルカリ土類金属ホウ素塩は除去したほう
が好ましい。窒化ホウ素粉末中のアルカリ土類金属ホウ
素塩は、例えば塩酸等の無機酸で処理すれば容易に除去
することができる。However, if the powder thus obtained is used as it is or after being pulverized, a large amount of alkaline earth metal borate will remain in the sintered body. This means that when the sintered body is heated to more than one thousand and several hundred degrees, it may be blown out in a liquid phase, so it is preferable to remove the alkaline earth metal boron salt. The alkaline earth metal boron salt in the boron nitride powder can be easily removed by treating with an inorganic acid such as hydrochloric acid.
本発明における粗粉原料粉末はどのような窒化ホウ素で
も構わないが、高密度で高強度の焼結体を得るためには
上記のように、窒化ホウ素粉末に種々処理を加えること
により、結晶性、純度を高めた粉末を用いることが好ま
しい。The coarse powder raw material powder in the present invention may be any boron nitride, but in order to obtain a high-density and high-strength sintered body, as described above, various treatments are applied to the boron nitride powder to obtain crystalline properties. It is preferable to use a powder with high purity.
更に、市販の窒化ホウ素粉末や、前述のように特定の物
質とともに加熱処理して結晶性を高めた粉末は、一般に
は粗くそのまま用いるのは適当でない。そこで本発明に
用いる粗粉はボールミル等により粉砕してBET比表面積
で１〜30m2/g程度にすることが必要である。Further, commercially available boron nitride powder and powder obtained by heat treatment with a specific substance to enhance crystallinity as described above are generally coarse and not suitable for use as they are. Therefore, it is necessary to pulverize the coarse powder used in the present invention with a ball mill or the like so as to have a BET specific surface area of about 1 to 30 m 2 / g.
又、超微粉原料粉末は市販の窒化ホウ素をボールミル等
で粉砕して100cm2/g以上にすることが必要である。ボー
ルミル容器内を窒素雰囲気にすれば比較的簡単に細かく
することができる。In addition, it is necessary to pulverize commercially available boron nitride with a ball mill or the like so that the raw material powder for ultrafine powder is 100 cm 2 / g or more. If the inside of the ball mill container is made into a nitrogen atmosphere, it can be made finer relatively easily.
次に、焼結体製造方法について具体的に説明する。以上
に述べたような２種類の粒度の窒化ホウ素粉末を配合し
これに0.1〜40重量％の炭化ホウ素粉末を加えてボール
ミル等を用いて湿式にて充分に混合し乾燥して顆粒とす
る。常圧のもとで焼結させる場合には配合原料を一旦金
型成形又はラバープレス或いはこれらの組み合せにより
所定形状で成形する。成形密度を上げるには1000kg/cm2
以上、好ましくは2000kg/cm2程度で加圧成形する。Next, a method for manufacturing a sintered body will be specifically described. The above-described two types of boron nitride powders having different particle sizes are blended, 0.1 to 40% by weight of boron carbide powder is added thereto, and the mixture is thoroughly mixed by a wet process using a ball mill or the like and dried to obtain granules. In the case of sintering under normal pressure, the compounded raw materials are once molded into a predetermined shape by die molding, rubber pressing, or a combination thereof. 1000kg / cm 2 to increase molding density
As described above, pressure molding is preferably performed at about 2000 kg / cm 2 .
勿論、生成形体の密度が充分にあげられるならば加圧成
形方法に限定されることなく、スリップキャスト法、押
し出し法等いずれの方法によっても構わない。Of course, the method is not limited to the pressure molding method as long as the density of the green molded body can be sufficiently increased, and any method such as a slip casting method and an extrusion method may be used.
得られた生成形体は黒く、これを窒素又は窒素を含有す
る非酸化性雰囲気で20〜200℃/minの昇温速度で1600℃
以上に昇温し、２〜10時間焼成して炭化ホウ素を窒素と
反応させて窒化ホウ素とすることにより白い焼結体とな
る。The obtained green form is black, and it is 1600 ° C at a heating rate of 20 to 200 ° C / min in nitrogen or a non-oxidizing atmosphere containing nitrogen.
The temperature is raised to the above temperature and the firing is performed for 2 to 10 hours to react boron carbide with nitrogen to form boron nitride, thereby forming a white sintered body.
ホットプレス法で焼結させる場合は配合原料を黒鉛ダイ
スに詰めて200〜400kg/cm2で加圧しながら高周波誘導加
熱炉等を用いて窒素雰囲気中で1800℃以上に加熱して焼
成すると黒鉛ダイスは通気性があるので、前記と同様に
反応して白い焼結体が得られる。When sintering by hot press method, the compounding raw material is packed in a graphite die and pressed at 200 to 400 kg / cm 2 and heated to 1800 ° C or higher in a nitrogen atmosphere using a high frequency induction heating furnace etc. Has a gas permeability, and reacts in the same manner as described above to obtain a white sintered body.
ここで窒化ホウ素の超微粉原料と炭化ホウ素の作用につ
いて説明する。Here, the action of the ultrafine powder material of boron nitride and boron carbide will be described.
超微粉原料は市販の窒化ホウ素粉末をボールミル等によ
って粉砕して100m2/g以上にすることが必要である。こ
の場合、ボールミル容器内を窒素等非酸化性雰囲気にす
ると、比較的容易に微粉砕することができ又窒化ホウ素
粉末の酸化が抑制できる。比表面積を上げるに従ってこ
れを配合した生成形体の密度は上げ難くくなり、焼結体
密度を低下させるが、焼結体強度を高める。又超微粉原
料の配合量は多いほうが焼結体強度は高くなるが、焼結
体密度を低下させる。For the ultrafine powder material, it is necessary to pulverize commercially available boron nitride powder with a ball mill or the like to 100 m 2 / g or more. In this case, if the inside of the ball mill container is made into a non-oxidizing atmosphere such as nitrogen, fine pulverization can be performed relatively easily, and oxidation of the boron nitride powder can be suppressed. As the specific surface area is increased, it becomes difficult to increase the density of the green compact containing this, and the density of the sintered body is lowered, but the strength of the sintered body is increased. Further, the larger the amount of the ultrafine powder material mixed, the higher the strength of the sintered body, but the density of the sintered body is lowered.
以上の事情により超微粉原料の好ましい比表面積は100
〜500m2/gであり、より好ましくは250〜400m2/gであ
る。又、超微粉原料の好ましい配合量は粗粉原料の50〜
90部に対し50〜10部であり、より好ましくは40〜20部で
ある。炭化ホウ素はその粒度が30μ以下好ましくは10μ
以下であるほうがよい。Due to the above circumstances, the preferable specific surface area of the ultrafine powder raw material is 100
˜500 m 2 / g, more preferably 250 to 400 m 2 / g. In addition, the preferable blending amount of the ultrafine powder raw material is 50 to 50% of the coarse powder raw material.
It is 50 to 10 parts, more preferably 40 to 20 parts, relative to 90 parts. Boron carbide has a particle size of 30μ or less, preferably 10μ
The following is better.
炭化ホウ素の添加量を0.1〜40重量％に限定したのは、
炭化ホウ素を添加しない場合は密度、強度ともに低い焼
結体しか得られず、40重量％をこえる場合には生成形体
密度が低下し、これを焼成しても密度の高い焼結体とな
らないからである。次いで、焼成条件について述べる。The amount of boron carbide added is limited to 0.1 to 40% by weight.
If boron carbide is not added, only a sintered body with low density and strength can be obtained, and if it exceeds 40% by weight, the density of the green compact will decrease, and even if this is sintered, a high density sintered body will not be obtained. Is. Next, firing conditions will be described.
焼成雰囲気は窒素又は窒素を含有する非酸化性であるこ
とが必要である。窒化ホウ素原料粉末に配合した炭化ホ
ウ素は雰囲気中の窒素と反応して窒化ホウ素に変換す
る。The firing atmosphere must be nitrogen or a non-oxidizing nitrogen-containing material. The boron carbide compounded in the boron nitride raw material powder reacts with nitrogen in the atmosphere and is converted into boron nitride.
焼成温度は、焼結体密度・強度を満足できる程度にまで
上げるだけならば1600℃以上あればよい。但し、1600℃
に近い温度で焼成して得られた焼結体は、配合した炭化
ホウ素及び又は成形用有機質バインダーに起因する黒色
部又は灰色部が特に焼結体内部に認められる。焼結体の
内部まで完全に白色化する為には、1800℃以上に加熱す
ることが必要であり、又、炭化ホウ素配合量が特に多い
場合、又は、成形体が大きい場合には1900℃以上に加熱
することが要求される。The firing temperature may be 1600 ° C. or higher if only raising the density and strength of the sintered body to a satisfactory level. However, 1600 ℃
In the sintered body obtained by firing at a temperature close to, a black portion or a gray portion due to the blended boron carbide and / or the organic binder for molding is particularly recognized inside the sintered body. In order to completely whiten the inside of the sintered body, it is necessary to heat it to 1800 ° C or higher, and if the boron carbide content is particularly large or if the compact is large, 1900 ° C or higher. It is required to heat up.
以上のようにして得られた焼結体の炭素含有量は、0.1
重量％以下と極めて少なく、窒化ホウ素に配合した炭化
ホウ素は焼成中に雰囲気の窒素と反応して完全に窒化ホ
ウ素に変化したことが認められた。The carbon content of the sintered body obtained as described above is 0.1
It was confirmed that the content of boron carbide was extremely small, at less than 10% by weight, and the boron carbide mixed with boron nitride was completely converted into boron nitride by reacting with nitrogen in the atmosphere during firing.
以下実施例、比較例により本発明を説明する。The present invention will be described below with reference to Examples and Comparative Examples.
〔実施例１〕 BET比表面積が5.5m2/gである市販の高純度窒化ホウ素粉
末をアルミナ製ポットミルを用いて粉砕し、BET比表面
積が15m2/gの粉末を得た。Example 1 A commercially available high-purity boron nitride powder having a BET specific surface area of 5.5 m 2 / g was pulverized using an alumina pot mill to obtain a powder having a BET specific surface area of 15 m 2 / g.
又、BET比表面積が4.5m2/gである市販の高純度窒化ホウ
素粉末をポットミルを用いてポット内の雰囲気を窒素に
保ちながら粉砕し、BET比表面積が375m2/gの超微粉末を
得たこれらの粒度を異にする２種類の粉末を15m2/gの粉
末80部に対して375m2/gの超微粉末20部の割合で配合
し、これの80重量％に平均粒子径が均１μの炭化ホウ素
を20重量％加えてこれらを水及び有機質バインダーとと
もにアルミナ製ポットミルを用いて20時間混合した。Further, a commercially available high-purity boron nitride powder having a BET specific surface area of 4.5 m 2 / g was crushed while maintaining the atmosphere in the pot with nitrogen using a pot mill, and a BET specific surface area of 375 m 2 / g ultrafine powder was obtained. The obtained two kinds of powders having different particle sizes were mixed in a ratio of 20 parts of 375 m 2 / g ultrafine powder to 80 parts of 15 m 2 / g powder, and 80% by weight of this powder was mixed with an average particle size. 20% by weight of 1 .mu.m of boron carbide was added, and these were mixed with water and an organic binder for 20 hours using an alumina pot mill.
噴霧乾燥により顆粒とした後金型で2000kg/cm2の圧力を
かけて成形した。得られた生成形体の密度は1.81g/cm2
であった。この生成形体を電気加熱式密閉炉に挿入し常
圧を保持しつつ窒素ガスを流しながら１時間に50℃の速
度で1800℃まで昇温し、２時間保持したのち炉内で冷却
し取り出した。得られた焼結体の密度は1.72g/cm2であ
った。又、焼結体より切り出した試験片（３×４×35m
m）の３点曲げ強度は463kg/cm2であった。After granulating by spray drying, a pressure of 2000 kg / cm 2 was applied with a mold to mold. The density of the obtained green form is 1.81 g / cm 2
Met. This green body was inserted into an electrically heated closed furnace, nitrogen gas was flowed while maintaining normal pressure, the temperature was raised to 1800 ° C. at a rate of 50 ° C. for 1 hour, and after holding for 2 hours, it was cooled and taken out in the furnace. . The density of the obtained sintered body was 1.72 g / cm 2 . Also, test pieces cut out from the sintered body (3 x 4 x 35 m
The 3-point bending strength of m) was 463 kg / cm 2 .
焼結体中のB2O3含有量は0.12重量％、炭素含有量は0.08
重量％であった。B 2 O 3 content in the sintered body is 0.12% by weight, carbon content is 0.08
% By weight.
〔実施例２〕 市販の窒化ホウ素粉末にCaO換算で５重量％となるよう
に酸化カルシウムとフッ化カルシウムを加え更にB2O3換
算で５重量％となるようにホウ酸を加え、混合しブリケ
ットと成したのち黒鉛るつぼに入れ、高周波誘導加熱炉
を用いて窒素ガス中で2000℃で２時間焼成した。冷却後
炉内より取り出しアルミナ製ボールミルで粉砕し、40メ
ッシュの篩で篩分けた。得られた窒化ホウ素1kgを12N塩
酸200ccと水20lとともにポリエチレン製容器に入れ、50
℃に加温しながら５時間攪拌した。次いで水を用いて洗
浄を繰り返し、洗浄水のpHが7.0となった時点でろ過し
乾燥した。得られた粉体は、B2O3含有量が0.36重量％で
あり、酸化カルシウム含有量が0.03重量％であった。[Example 2] Calcium oxide and calcium fluoride were added to a commercially available boron nitride powder so as to be 5% by weight in terms of CaO, and boric acid was further added so as to be 5% by weight in terms of B 2 O 3 and mixed. After forming into a briquette, it was put into a graphite crucible and fired in a nitrogen gas in a high-frequency induction heating furnace at 2000 ° C. for 2 hours. After cooling, it was taken out of the furnace, pulverized with an alumina ball mill, and sieved with a 40-mesh sieve. 1 kg of the obtained boron nitride was put in a polyethylene container together with 200 cc of 12N hydrochloric acid and 20 liters of water.
The mixture was stirred for 5 hours while warming to ℃. Then, washing with water was repeated, and when the washing water reached pH 7.0, it was filtered and dried. The obtained powder had a B 2 O 3 content of 0.36% by weight and a calcium oxide content of 0.03% by weight.
このようにして得た高結晶性、高純度窒化ホウ素粉末を
ボールミルを用いて粉砕し比表面積を23m2/gとした。こ
の窒化ホウ素粉末の70部に実施例１で得られた比表面積
が375m2/gの超微粉窒化ホウ素を30部配合しこれの90重
量％に平均粒子径が約１μの炭化ホウ素を10重量％加え
てこれらを水及び有機質バインダーとともにアルミナ製
ポットミルを用いて20時間混合した。以後は実施例１と
同様にして焼結体を作製した。The highly crystalline and highly pure boron nitride powder thus obtained was crushed using a ball mill to have a specific surface area of 23 m 2 / g. 70 parts of this boron nitride powder was blended with 30 parts of ultrafine boron nitride having a specific surface area of 375 m 2 / g obtained in Example 1, and 90% by weight thereof was added with 10 parts by weight of boron carbide having an average particle size of about 1 μ. %, And these were mixed with water and an organic binder for 20 hours using an alumina pot mill. Thereafter, a sintered body was produced in the same manner as in Example 1.
ここで得られた生成形体の密度は1.90g/cm2であった
又、焼結体の密度は1.76m2/gであり３点曲げ強度は627k
g/cm2であった。焼結体中のB2O3含有量は0.15重量％炭
素含有量は0.05重量％であった。The green body obtained here had a density of 1.90 g / cm 2 , and the sintered body had a density of 1.76 m 2 / g and a three-point bending strength of 627 k.
It was g / cm 2 . The B 2 O 3 content in the sintered body was 0.15% by weight, and the carbon content was 0.05% by weight.
〔比較例１〕 炭化ホウ素を配合しないほかは実施例１と同様にして作
製した焼結体の密度は1.61g/cm3であり３点曲げ強度は2
65kg/cm2であった。[Comparative Example 1] The density of a sintered body produced in the same manner as in Example 1 except that boron carbide was not mixed was 1.61 g / cm 3 , and the three-point bending strength was 2
It was 65 kg / cm 2 .
〔比較例２〕 BET比表面積が15m2/gの窒化ホウ素に平均粒子径が約１
μの炭化ホウ素を20重量％加えて以後実施例１と同様に
して焼結体を作製した。ここで得られた焼結体の密度は
1.71g/cm3であり、曲げ強度は189kg/cm2であった。また
1700℃で２時間焼成した焼結体は内部に黒灰色部が認め
られ、Ｘ線回析による分析で少量の炭化ホウ素が析出さ
れ、焼成中の炭化ホウ素から窒化ホウ素への変換が充分
でなかった。Comparative Example 2 Boron nitride having a BET specific surface area of 15 m 2 / g and an average particle size of about 1
20% by weight of boron carbide (μ) was added, and thereafter a sintered body was prepared in the same manner as in Example 1. The density of the sintered body obtained here is
It was 1.71 g / cm 3 and the bending strength was 189 kg / cm 2 . Also
A black gray portion was observed inside the sintered body that was fired at 1700 ° C for 2 hours, and a small amount of boron carbide was precipitated by analysis by X-ray diffraction, and the conversion of boron carbide to boron nitride during firing was insufficient. It was
以上の実施例から分るようにBET比表面積で１〜30m2/g
の窒化ホウ素粉末とBET比表面積で100m2/g以上の窒化ホ
ウ素粉末を粒度配合しこれに炭化ホウ素粉末を加えれば
常圧のもとでも緻密に焼結し、その焼結体は従来のホッ
トプレス窒化ホウ素に匹敵する強度を有している。更に
この焼結体は純度が高く不活性雰囲気中で1800℃に加熱
しても全く変化がなく熱的に安定である。As can be seen from the above examples, the BET specific surface area is 1 to 30 m 2 / g.
Boron nitride powder and BET specific surface area of 100m 2 / g or more of boron nitride powder are mixed in particle size, and if boron carbide powder is added to this, it sinters densely under normal pressure It has strength comparable to that of pressed boron nitride. Further, this sintered body has a high purity and is thermally stable with no change even when heated to 1800 ° C. in an inert atmosphere.
このように本発明によれば安価で高品位窒化ホウ素焼結
体が得られるのでこの焼結体は今後耐熱性、耐熱衝撃
性、潤滑性、耐蝕性、電気絶縁性、熱伝導性が要求され
る分野で活用されることが期待できる。As described above, according to the present invention, a high-quality boron nitride sintered body can be obtained at a low cost, so that this sintered body is required to have heat resistance, thermal shock resistance, lubricity, corrosion resistance, electrical insulation, and thermal conductivity in the future. It can be expected to be utilized in various fields.
Claims (1)
/g以上の粉末を配合してなる六方晶窒化ホウ素の混合粉
末60〜99.9重量％と炭化ホウ素粉末0.1〜40重量％を配
合して成形し、窒素又は窒素を含有する非酸化性雰囲気
中で炭化ホウ素を窒化ホウ素に変換させる温度以上で焼
成することを特徴とする窒化ホウ素焼結体の製造方法。1. A BET specific surface area of 1-30 m 2 / g powder and 100 m 2
Hexagonal boron nitride mixed powder 60 to 99.9% by weight and 0.1 to 40% by weight of boron carbide powder are mixed and molded in a non-oxidizing atmosphere containing nitrogen or nitrogen. A method for producing a boron nitride sintered body, which comprises firing at a temperature equal to or higher than a temperature at which boron carbide is converted to boron nitride.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62259653A JPH0735303B2 (en) | 1987-10-16 | 1987-10-16 | Method for manufacturing boron nitride sintered body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62259653A JPH0735303B2 (en) | 1987-10-16 | 1987-10-16 | Method for manufacturing boron nitride sintered body |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01103959A JPH01103959A (en) | 1989-04-21 |
| JPH0735303B2 true JPH0735303B2 (en) | 1995-04-19 |
Family
ID=17337039
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62259653A Expired - Lifetime JPH0735303B2 (en) | 1987-10-16 | 1987-10-16 | Method for manufacturing boron nitride sintered body |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0735303B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104470873A (en) * | 2012-06-27 | 2015-03-25 | 水岛合金铁株式会社 | Sintered spherical BN particles with concave part, method for producing same, and polymer material |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2531871B2 (en) * | 1991-06-18 | 1996-09-04 | 昭和電工株式会社 | Method for manufacturing high-density boron nitride pressureless sintered body |
-
1987
- 1987-10-16 JP JP62259653A patent/JPH0735303B2/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104470873A (en) * | 2012-06-27 | 2015-03-25 | 水岛合金铁株式会社 | Sintered spherical BN particles with concave part, method for producing same, and polymer material |
| US9334391B2 (en) | 2012-06-27 | 2016-05-10 | Mizushima Ferroalloy Co., Ltd. | Sintered spherical BN particles, method of producing the same, and polymer material |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01103959A (en) | 1989-04-21 |
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